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Biomedical subjects

A Yamada

Publications and source records attributed to A Yamada.

At least 37 records · Page 2Linked to original sources
PubMed2003

Persistence of systolic coronary flow reversal predicts irreversible dysfunction after reperfused anterior myocardial infarction.

OBJECTIVE: To investigate serial assessments of systolic coronary flow reversal in the infarct related artery for predicting poor left ventricular functional recovery after reperfused acute myocardial infarction. SETTING: Regional hospital. PATIENTS AND METHODS: 49 patients with anterior acute myocardial infarction had transthoracic Doppler echocardiography to record coronary flow velocity in the left anterior descending coronary artery immediately after successful primary coronary angioplasty (day 0), and at 48 hours, one week, and three weeks. MAIN OUTCOME MEASURES: Coronary flow velocity at each time point; regional wall motion score index (RWMSI) at day 0 and at three weeks. Irreversible dysfunction was defined as a decrease in RWMSI to < 0.22. RESULTS: Measurements of coronary flow velocity could be made in 45 patients. Patients were divided into three groups: no systolic flow reversal (group 1, n = 27), systolic flow reversal observed only on day 0 (group 2, n = 8), and systolic flow reversal persisting until 48 hours (group 3, n = 10). Although baseline RWMSI was similar among the three groups, the value at three weeks was significantly higher in group 3 than in the other two groups. In predicting irreversible dysfunction, the persistence of systolic flow reversal up to 48 hours had a higher positive predictive value (100%) than the presence of systolic flow reversal on day 0 (67%, p < 0.04). The negative predictive value of systolic flow reversal at 48 hours (83%) was comparable in accuracy to the presence of systolic flow reversal on day 0 (85%, NS). CONCLUSIONS: In reperfused anterior acute myocardial infarction, serial assessment of coronary flow velocity in the left anterior descending coronary artery is feasible using transthoracic Doppler echocardiography, and the persistence of systolic flow reversal at 48 hours is a more specific marker of irreversible dysfunction than peak creatine kinase or diastolic deceleration time.

Adult↗
PubMed2002

UDP-Gal: betaGlcNAc beta1, 3-galactosyltransferase, polypeptide 3 (GALT3) is a tumour antigen recognised by HLA-A2-restricted cytotoxic T lymphocytes from patients with brain tumour.

Patient prognosis in the case of malignant brain tumours is generally poor, despite significant improvements in the early detection of the tumours, and thus the development of new treatment modalities is needed. One of the most prominent modalities is specific immunotherapy, for which the elucidation of antigenic molecules of malignant brain tumours recognized by T cells is essential. We report here a gene, UDP-Gal: betaGlcNAc beta1, 3-galactosyltransferase, polypeptide 3, encoding three epitope peptides recognised by tumor-reactive cytotoxic T lymphocytes in an HLA-A2-restricted manner. Two of the three peptides possessed an ability to induce HLA-A2-restricted and tumour-reactive cytotoxic T lymphocytes from peripheral blood mononuclear cells of patients with brain tumours. These peptides may be useful in the peptide-based specific immunotherapy for patients with malignant brain tumours.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed2002

Increased plasma HB-EGF associated with obesity and coronary artery disease.

The mechanism by which the obese subjects are more associated with vascular disease remains unclear. We reported that the adipose tissues produce and secrete many bioactive molecules, conceptualized as adipocytokines. Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), produced locally by vascular macrophages and smooth muscle cells, has been suggested to induce the migration and proliferation of vascular smooth muscle cells. The current study reveals that (1) HB-EGF mRNA is abundantly expressed in human adipose tissue, (2) HB-EGF mRNA increases in the fat tissues of obese mice, (3) plasma HB-EGF levels increase in parallel with fat accumulation in human, and (4) the subjects with coronary artery disease have higher plasma HB-EGF levels, associated with fat accumulation. These results suggest that increased plasma HB-EGF derived from the accumulated fat contributes to the higher incidence of vascular disease in obesity, proposing HB-EGF as an adipocytokine directly linking adipovascular axis.

Adipose Tissue↗
PubMed2002

Room temperature scanning Hall probe microscopy using GaAs/AlGaAs and Bi micro-hall probes.

A room temperature scanning Hall probe microscope system utilizing GaAs/AlGaAs and bismuth micro-Hall probes was used for magnetic imaging of ferromagnetic domain structures on the surfaces of crystalline thin film garnets and permanent magnets. The Bi micro-Hall probes had dimensions ranging between 0.25 and 2.8 microm2 and were fabricated using a combination of optical lithography and focused ion beam milling. The use of bismuth was found to overcome surface depletion effects associated with semiconducting micro-Hall probes. Our experiments demonstrated that Bi is a practical choice of material for fabricating sub-micron sized Hall sensors.

Journal Article↗
PubMed2002

Non-mutated tumor-rejection antigen peptides elicit type-I allergy in the majority of healthy individuals.

IgE-mediated type-I allergy is generally considered to be a hypersensitivity reaction to foreign antigens, and it is believed that self-antigens do not evoke this type of allergy. We report here, for the first time, that non-mutated self-antigen peptides identified as tumor-rejection antigen peptides recognized by HLA class I-restricted and tumor-specific cytotoxic T lymphocytes (CTLs) elicited a type-I allergy in the majority of healthy individuals. Peptide-specific IgE was detectable in sera from certain cases, although the levels did not always correlate with those of type-I allergy. Repeated vaccinations of nonallergic peptides derived from the same antigens possessing allergic peptides resulted in the suppression of both allergic peptide-specific IgE responses and type-I allergy, providing evidence for a new approach to the development of peptide-based desensitization.

Adult↗
PubMed2002

[Minimal incision abdominal aortic aneurysm repair].

OBJECTIVE: The use of a limited incision for abdominal aortic aneurysm (AAA) repair was evaluated, and its outcome was analyzed in comparison to standard open repair. PATIENTS AND METHODS: Between February 2000 and August 2001, 20 patients with an AAA underwent minimal incision repair (MINI) for tube graft implantation. The minimal skin incision was made after localization of aneurysm neck and aortic bifurcation by CT and DSA. For repair of the upper part of the AAA the abdominal incision was retracted toward the head of the patient who was in a jackknife decubitus position. Conversely, when the peripheral portion of the AAA was treated, the abdominal incision was retracted caudally with the patient in a flat or slightly bent decubitus position. The operation itself was performed using the standard conventional technique. The length of the abdominal incision was 10 cm. Clinical characteristics and in-hospital outcome of this procedure were compared to a group of patients who underwent repair of AAA by means of a standard open technique (OPEN). RESULTS: Patients age in the MINI and OPEN groups were similar (69 +/- 11 vs. 69 +/- 9 years). However, there were significant differences between the MINI and OPEN groups in the time for starting oral intake of food (2,4 +/- 1,2 vs. 7,4 +/- 5,5 postoperative days, p = 0,003), time for starting to walk outside the room (2,2 +/- 0,7 vs. 4,6 +/- 2,2 postoperative days, p = 0,01) and operation times (197 +/- 37 vs. 294 +/- 83 min, p = 0,0004). CONCLUSION: Minimal incision repair is technically feasible and combines the benefits of a minimal incision with those of conventional open repair, reducing patient recovery time.

Aged↗
PubMed2002

Personality, social support, coping and emotional distress after repeated spontaneous abortions.

Systematic investigations on the emotional impacts of repeated spontaneous abortions have been few. We mounted a prospective study of a cohort of couples who had experienced two consecutive first trimester spontaneous abortions and for whom no clearly identifiable causes were found. The present report is based on the first part of the study and examines: (1) emotional distress reported by the miscarrying women at six months (median, range 1-12 months) after two abortions; and (2) psychosocial predictors influencing such distress. The mean score of the women on the Symptom Checklist 90-Revised--one of the most popular self-report scales for psychopathology--was 0.38, whereas that for the general population is reported to be 0.26 (the higher the score, the more psychopathology). Fourteen percent of the cohort scored above the cutoff point for mental disorders screening. Factors examined and found non-influential upon the level of emotional distress include: the maternal age; whether the last pregnancy was planned and wished for or not; and coping styles of the women after the abortions. Control by the husbands over the marital relationship and neurotic personality traits of the women increased the emotional distress, whereas the social support the women perceive decreased it. These findings suggest that martial and social support are important in determining the level of psychiatric morbidity after repeated abortions.

Abortion, Spontaneous↗
PubMed2002

Calcium-sensing receptor gene polymorphism affects the parathyroid response to moderate hypercalcemic suppression in patients with end-stage renal disease.

AIM: The basic mechanism of secondary hyperparathyroidism is still unclear, but a change in Ca2+ sensing by parathyroid cells is possibly involved in this uremic complication. A rightward shift of the calcium set-point and an increase of the minimum secretion rate have been found in secondary hyperparathyroidism, indicating abnormal calcium sensing. METHODS: We evaluated the effect of calcium sensing receptor (CaR) gene polymorphism (codon G990R) on the response of the parathyroid gland to moderate hypercalcemic suppression in 77 ESRD patients on regular hemodialysis (HD using 2.5 mEq/l Ca2+ dialysate). All patients underwent an HD session with 3.0 mEq/l Ca2+ dialysate to suppress parathyroid hormone (PTH). Then we investigated the effect of CaR gene polymorphism on the parathyroid response to hypercalcemic stimulation. RESULTS: Patients were divided into 3 groups on the basis of genotype (GG = 33 patients (42.9%), GR = 39 patients (50.6%), RR = 5 patients (6.5%)). Baseline intact PTH levels in patients without the R allele were not significantly different from those in patients with the R allele (GG group, 181.4 +/- 31.1 pg/ml vs. GR and RR groups, 230 +/- 51.2 pg/ml: mean +/- SEM). The significant effect of moderate hypercalcemic suppression on the intact PTH level was observed in the GG group (p < 0.01) but not in the GR and RR groups, despite the identical increase in Ca2+. CONCLUSION: Our results suggest that CaR gene polymorphism (codon G990R) influences the responsiveness of the parathyroid gland to changes of extracellular Ca2+ in ESRD patients. The glands of patients with the GG genotype of the CaR gene may be more sensitive to extracellular Ca2+ changes.

Calcium↗
PubMed2002

[Surgical treatment of cardiovascular manifestations of Marfan syndrome].

The present study determines the effect of surgical treatment of cardiovascular manifestations of Marfan syndrome in 72 patients by 114 operations, during 34-year period. This therapy resulted in aortic root repair, aortic arch replacement, or both in 78, mitral valve repair in 9, descending thoracic aortic replacement in 14, thoracoabdominal aortic replacement in 10, and abdominal aortic replacement in 6, including total aortic replacement in 4 and nearly total aortic replacement in 4 patients. Fusiform aneurysms were present in the the ascending aorta in 37, the aortic arch in 2, the thoracoabdominal aorta in 2, and the abdominal aorta in 6 patients. Aortic dissection occurred in 40 (55.6%), including type A aortic dissection in 29 patients. Aortic root repair included separate valve-graft in 8, Bentall composite valve-graft in 25, composite valve-graft with button technique in 26, composite valve-graft with interposition graft technique in 10, and valve sparing procedure in 5 patients. The overall early (30-day) mortality was 7.9%. The early survival was 75% in separate valve-graft procedure and 99.2% in composite valve-graft procedure. Late coronary dehiscence did not occur in the patients with Bentall technique in which the reattachments of coronary ostia were performed in 2 layers, but occurred in 50% of patients with the coronary anastomoses in 1 layer. Aortic valve regurgitation relapsed in 2 of the 5 patients with valve sparing procedure. Event free rate for the patients with composite valve-graft using button technique was 81.1% at 10 years. There were 14 late deaths; dissection or rupture of the residual aorta, composite graft endocarditis and cardiac failure were the principle causes of late deaths. In conclusion, Marfan patients with cardiovascular diseases can undergo surgical treatment with a low operative risk and low morbidity. Although late endocarditis remains a serious problem, we believe that Marfan syndrome is a contraindication for valve sparing procedure. Because of the potential for late dissection or aneurysm in other areas of the aorta, patients with Marfan syndrome should have serial computed tomographic scans indefinitely.

Adolescent↗
PubMed2001

Suppression of membrane-type 1 matrix metalloproteinase (MMP)-mediated MMP-2 activation and tumor invasion by testican 3 and its splicing variant gene product, N-Tes.

Using expression cloning to screen a human fetal kidney cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2 processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose product interfered with pro-MMP-2 activation. It encodes the NH(2)-terminal 313-amino acid region of a calcium-binding proteoglycan, testican 3, with a 3-amino acid substitution at the COOH terminus and thus was named N-Tes. N-Tes comprises a signal peptide, a unique domain, a follistatin-like domain, and a Ca(2+)-binding domain but lacks a COOH-terminal thyroglobulin domain and two putative glycosaminoglycan attachment sites of testican 3. Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct interaction of N-Tes with either MT1-MMP or MT3-MMP. Expression of testican 1 or testican 3 but not testican 2 also inhibited pro-MMP-2 activation by either MT1-MMP or MT3-MMP. Deletion and substitution of amino acids residues in N-Tes revealed that the unique NH(2)-terminal domain of N-Tes is responsible for the inhibition of pro-MMP-2 activation by MT-MMPs. Expression of N-Tes and testican 3 was detected in normal brain but down-regulated in glioma tissues. Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel. These results suggest that both N-Tes and testican 3 would interfere with tumor invasion by inhibiting MT-MMPs.

Alternative Splicing↗
PubMed2001

Recipient MHC class II expression is required to achieve long-term survival of murine cardiac allografts after costimulatory blockade.

To study the role of the direct and indirect pathways in achieving tolerance, we used genetically altered mouse strains in two ways: 1) MHC class II-deficient mice were used as donors of skin and cardiac grafts to eliminate the direct CD4(+) T cell response, and 2) B6 II(-)4(+) mice, which are MHC class II-deficient mice expressing an MHC class II transgene only on thymic epithelium, were used as recipients of normal grafts. These mice cannot mount an indirect response. Eliminating the indirect pathway actually made it more difficult to achieve prolonged allograft survival when we used costimulatory blockade than when both pathways were available. Costimulatory blockade was ineffective even when CD4(+) T cells from normal animals were transferred into recipients that lacked MHC class II molecules. These results suggest that an active CD4(+) response through the indirect pathway is necessary for costimulatory blockade to be effective in prolonging allograft survival.

Abatacept↗
PubMed2001

Identification of Lck-derived peptides capable of inducing HLA-A2-restricted and tumor-specific CTLs in cancer patients with distant metastases.

The Lck protein (p56(lck)), a src family tyrosine kinase essential for T cell development and function, is aberrantly expressed in various types of cancers. We revealed recently that Lck can be a tumor antigen recognized by HLA-A24-restricted and tumor-specific cytotoxic T lymphocytes (CTLs) of cancer patients with metastases. In this study, we tried to identify Lck-derived epitopes capable of inducing HLA-A2-restricted and tumor-specific CTLs in cancer patients. The tumor-infiltrating lymphocytes (TILs) from 2 HLA-A2 cancer patients were found to respond to COS-7 cells when co-transfected with the lck gene and either HLA-A0201, -A0206, or A0207 cDNA. These TILs contained CTLs capable of recognizing either the Lck(61-69), the Lck(246-254), or the Lck(422-430) peptide among 24 different peptides, all of which were prepared based on the HLA-A2 binding motif. Importantly, in vitro sensitization with the latter 2 peptides induced tumor-specific CTLs in HLA-A2(+) cancer patients with metastases, but not in those without metastases. Overall, the Lck(246-254) and Lck(422-430) peptides could be useful for specific immunotherapy of HLA-A2(+) cancer patients, especially with distant metastases.

Animals↗
PubMed2001

Binding of a SART3 tumor-rejection antigen to a pre-mRNA splicing factor RNPS1: a possible regulation of splicing by a complex formation.

We recently reported the identification of a human SART3 gene that encodes a tumor-rejection antigen recognized by cytotoxic T lymphocytes (CTLs). The squamous-cell carcinoma antigen recognized by T cells-3 (SART3) is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. To determine its biologic function, we employed a 2-hybrid screening in yeast for proteins interacting with SART3, and this method yielded a pre-mRNA splicing factor (RNA-binding protein prevalent during the S phase or RNA-binding protein with a serine-rich domain [RNPS1]) that activated both constitutive and alternative splicing of pre-mRNA in vitro. Interaction of SART3 with RNPS1 through the physical association of N-terminal domains of RNPS1 was confirmed by both in vitro pull-down assay and immunoprecipitation assay. Cotransfection of the 2 genes changed the distribution pattern of SART3 from diffuse nucleoplasmic spreading to nuclear speckled regions in which the RNPS1 was colocalized, suggesting a complex formation of the 2 proteins. In cooperation with RNPS1, SART3 stimulated the proximal alternative 3' splicing of a calcitonin-dihydrofolate reductase chimeric minigene pre-mRNA. These results suggest that SART3 is involved in the regulation of mRNA splicing probably via its complex formation with RNPS1.

Antigens, Neoplasm↗
PubMed2001

Multidrug resistance-associated protein 3 is a tumor rejection antigen recognized by HLA-A2402-restricted cytotoxic T lymphocytes.

The identification of tumor rejection antigens recognized by CTLs and its application in peptide-based specific immunotherapy against melanomas have been extensively investigated in the past decade. However, only a small number of studies regarding these issues in other epithelial cancers have been reported. In this study, we show that a multidrug resistance-associated protein 3 (MRP3) is a tumor rejection antigen recognized by HLA-A2402-restricted CTLs established from T cells infiltrating into lung adenocarcinoma. MRP3 is expressed in differing quantities in tumor cells of various tissue types and origins. Four dominant MRP3-derived antigenic peptides that are recognized by the CTLs have been identified, each possessing in vitro immunogenicity. Namely, these four peptides (MRP3-503, MRP3-692, MRP3-765, and MRP3-1293) can induce peptide-specific CTLs after in vitro stimulation with these peptides in peripheral blood mononuclear cell cultures of HLA-A24(+) cancer patients, with the CTLs expressing cytotoxicity against HLA-A2402(+) MRP3(+) tumor cells but not against either HLA-A2402(-) or MRP3(-) target cells. The peptide specificity of the cytotoxicity of the CTLs was further confirmed by using peptide-loaded HLA-A24(+) EBV-transformed B cells. Widespread MRP3 expression in various tumor cell lines and tumor tissues at the mRNA level was confirmed. Furthermore, reactivities of the MRP3-peptide-induced CTLs against tumor cells correlated with MRP3 expression in the tumor cells. These results suggest that MRP3 and its derived peptides described in the present paper are potential candidates for cancer vaccines in regard to HLA-A24(+) patients with various tumors, particularly for those tumors that show anticancer drug resistance.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2001

Production of polyunsaturated fatty acids by polyketide synthases in both prokaryotes and eukaryotes.

Polyunsaturated fatty acids (PUFAs) are essential membrane components in higher eukaryotes and are the precursors of many lipid-derived signaling molecules. Here, pathways for PUFA synthesis are described that do not require desaturation and elongation of saturated fatty acids. These pathways are catalyzed by polyketide synthases (PKSs) that are distinct from previously recognized PKSs in both structure and mechanism. Generation of cis double bonds probably involves position-specific isomerases; such enzymes might be useful in the production of new families of antibiotics. It is likely that PUFA synthesis in cold marine ecosystems is accomplished in part by these PKS enzymes.

Anaerobiosis↗
PubMed2001

CD28-independent costimulation of T cells in alloimmune responses.

T cell costimulation by B7 molecules plays an important role in the regulation of alloimmune responses. Although both B7-1 and B7-2 bind CD28 and CTLA-4 on T cells, the role of B7-1 and B7-2 signaling through CTLA-4 in regulating alloimmune responses is incompletely understood. To address this question, we transplanted CD28-deficient mice with fully allogeneic vascularized cardiac allografts and studied the effect of selective blockade of B7-1 or B7-2. These mice reject their grafts by a mechanism that involves both CD4(+) and CD8(+) T cells. Blockade of CTLA-4 or B7-1 significantly accelerated graft rejection. In contrast, B7-2 blockade significantly prolonged allograft survival and, unexpectedly, reversed the acceleration of graft rejection caused by CTLA-4 blockade. Furthermore, B7-2 blockade prolonged graft survival in recipients that were both CD28 and CTLA-4 deficient. Our data indicate that B7-1 is the dominant ligand for CTLA-4-mediated down-regulation of alloimmune responses in vivo and suggest that B7-2 has an additional receptor other than CD28 and CTLA-4 to provide a positive costimulatory signal for T cells.

Abatacept↗
PubMed2001

Crystal structure of 2-hydroxyl-6-oxo-6-phenylhexa-2,4-dienoic acid (HPDA) hydrolase (BphD enzyme) from the Rhodococcus sp. strain RHA1 of the PCB degradation pathway.

2-Hydroxyl-6-oxo-6-phenylhexa-2,4-dienoic acid (HPDA) hydrolase (the BphD enzyme) hydrolyzes a ring-cleavage product of an aromatic compound generated in a biphenyl/polychlorinated biphenyl (PCB) degradation pathway of bacteria. The crystal structure of the BphD enzyme has been determined at 2.4 A resolution by the multiple isomorphous replacement method. The final refined model of the BphD enzyme yields an R-factor of 17.5 % at 2.4 A resolution with reasonable geometry. The BphD enzyme is an octameric enzyme with a 422 point-group symmetry. The subunit can be divided into core and lid domains. The active site of the enzyme is situated in the substrate-binding pocket, which is located between the two domains. The substrate-binding pocket can be divided into hydrophobic and hydrophilic regions. This feature of the pocket seems to be necessary for substrate binding, as the substrate is composed of hydrophilic and hydrophobic parts. The proposed orientation of the substrate seems to be consistent with the general catalytic mechanism of alpha/beta-hydrolases.

Amino Acid Sequence↗